Upvote:13
This does seem to be confirmed via several sources. The book Harry S. Truman: His Life and Times By Brian Burnes mentions Truman's music on page 14, where after Eugene List had played, it says
"Then Truman himself took a turn at the keyboard"
Other sources discussing this include:
So there appears to be no shortage of reports of Truman's piano use at the conference.
As to Churchill's discomfort, it is also discussed in sources such as Presidential Diversions: Presidents at Play... By Paul F. Boller, where it quotes Churchill, the next day during the lengthy classical performance put on by Stalin's musicians, as saying
"I'm bored to tears. I do not like the music"
So Churchill's discomfort seems to be confirmed as well. The only thing I have not been able to confirm is Truman actually playing Chopin; it seems this was left to List in the sources I have found.
Upvote:18
According to one of his letters to his wife Bess, Truman noticed that Stalin liked Chopin's music very much, especially the version played by the American pianist at Potsdam. And Chopin was also one of Truman's favorite composers (alongside German composers that Stalin would not have liked).
And Truman wanted "both of them in it" (the war with Japan). Britain was already involved, so Stalin, who had signed a five-year non aggression pact with Japan, was the one that needed convincing.
Truman was a competent, though not professional level pianist, so it would make sense that he would play "his" Chopin to cater to Stalin. He had no reason to annoy Churchill, except for the fact that Churchill was (possibly) "annoyed."